MONTE CARLO SIMULATION OF In/GaAs DROPLET EPITAXY PROCESSES ON STRUCTURED SUBSTRATES

O.A. Ageev, M.M. Eremenko, N.E. Chernenko, M.S. Solodovnik, S.V. Balakirev
2019 IZVESTIYA SFedU ENGINEERING SCIENCES  
The paper presents the results of theoretical studies of self-organization of nanoscale metal droplets obtained by droplet epitaxy in an In/GaAs (001) system on substrates with pre-defined structural inhomogeneities using our original hybrid mathematical model of droplet epitaxy developedbased on a combination of Monte Carlo method and thermodynamic theory of nucleation. We varied the shape and geometric characteristics of the specified grooves, as well as the distance between them (density).
more » ... e processes of nucleation and growth of droplet nanostructures on structured GaAs surfaces were considered taking into account the main control parameters of the droplet epitaxy technique. The calculation results showed that on substrates with complex morphology, the probability of island nucleation is distributed non-uniformly and depends on the surface area. The study shows that in order to achieve the best homogeneity of the geometric characteristics of nanostructures on substrates with rectangular grooves, the diameter of the groove should be reduced, adjusting the height so as to achieve an effective volume and aspect ratio. On substrates with trapezoid-shaped grooves, the embryo forms approximately in the center of the grooves, with a large base ratio. We show that in order to improve the accuracy of nanostructure positioning and their homogeneity, triangular- shaped grooves with large aspect ratios of geometrical sizes are most preferable. In all cases, regardless of the groove geometry, the preferred position for the nucleation of metallic nanodroplets is the groove bottom, which is caused by an increase in the number of substrate atoms surrounding the adatom, and, consequently, an increase in its binding energy with the current environment. At the same time, for all considered forms of inhomogeneities, an increase in their effective depth (aspect ratio) leads to a decrease in the probability of the droplet formation beyond their limits and an improvement in the localization of growth processes. The use of modified [...]
doi:10.23683/2311-3103-2019-2-174-184 fatcat:z27hxc3svffklexh3feljlovwy